At present, in the printing sector, and in particular in the sector of printing labels and flexible wrappings, there exists a very urgent need to increase the general efficiency of the printing processes, on the one hand reducing the printing time and on the other hand limiting the wastage of material, such as the printing medium.
In particular, the step of changing the printing rollers is one of the most critical steps in the entire printing process since the so-called “job change-over” times constitute downtime, during which the printing process is substantially interrupted. Moreover, the change-over between two different printing jobs generally results in a huge amount of wasted material.
Some solutions for automatically changing the printing rollers are known. For example reference is made to international publication WO2009/144016. This describes a printing machine associated with a device which performs replacement of the printing roller with a new one. This device comprises gripping means displaceable on a guide for gripping the used printing roller, depositing it in a suitable store, gripping a new printing roller and then arranging it in the working position. This device is constructionally complex and bulky. Moreover, replacement of the printing roller is relatively slow because it requires successive and consequent movements of the same gripping element.